Free (open access)
Taking profit of the knowledge of lamps with expandable arms, fixed on the walls, or on the table, we have decentred the pinned join in order to achieve an arch, when the arm is expanded. The analysis of this structure has to deal with two situations: when the arch is wholly expanded, working in compres- sion and when the arch is expanding, working in flexion. Delimiting cables can be fixed on the external joints so that certain improvement of flexion re- sistance can be gained. If a textile membrane is attached to the inner joints, not only an arch but a real vault is obtained when unfolding the structure. Posterior pretension of this membrane can solve the stability of the whole construction. Half arches can produce a dome, by solving the top joint where all arches converge. Automatic expansion is also studied in this research.